The present invention relates to a method for producing dyed textile materials made of polyester and polyamide.
Dyeing methods for polyester and polyamide fibers are known from the literature (see Ullmann""s Encyclopaedia of Industrial Chemistry, 6th Edition, 1998). There, disperse dyestuffs are preferably suggested for dyeing polyester fibers, and acid dyestuffs for dyeing polyamide fibers.
In addition, several dyeing methods are known from the literature for polyester/polyamide microfiber mixtures (brochure of the firm Sandoz Chemical AG).
In that case, dyeing
a) should be performed using only disperse dyestuffs, having the disadvantage that, beginning at a certain depth of color, two color effects appear;
b) using two classes of dyestuff is performed, and bicolor effects are consciously accepted;
c) is two-bath, whereby, to be sure, color fastness can be improved, but costs go up at the same time, and
d) is single-bath, whereby, however, available color combinations are severely limited.
Especially for medium and deep color tones, color fastness is achieved only up to 40xc2x0 C.
For the present invention, the object was set to describe a method which permits the production of dyed textile materials, made of polyester and polyamide, and permits a wash resistance for medium and deep color shades up to at least 60xc2x0 C.
According to the present invention the object is attained in that the textile material is dyed with disperse dyestuffs which dye polyester or with pigments, excess dyestuff is removed, and dyeing the polyamide portion is undertaken with the aid of vat dyestuff, leuco vat dyestuffs, sulfide dyestuffs or soluble sulfide dyestuffs, and in case it is necessary to achieve their solubility, the above-named dyestuffs being vatted, and, after dye take-up, being oxidatively converted to the fast dyestuff. In this manner wash resistance up to at least 60xc2x0 C. is achieved, even for medium and deep color shades. On top of that, no special aftertreatment is necessary to achieve such colorfastness, and thereby savings are achieved with respect to chemicals and the water necessary for carrying out the method.
Dyeing the polyamide portion is preferably undertaken using vat dyestuffs. Vat dyestuffs have proven to be the most stable with respect to their fastness to light and wetness (resistance to washing, water and perspiration).
One method is particularly preferred in which one first dyes the polyester portion with disperse dyestuffs, subsequently carries out a reductive cleaning at ca 80xc2x0 C., and then dyes the polyamide portion. This advantageous variant of the method leads to greater wetfastness of the dyed materials.
A further preferred variant of the method is to conduct the dyeing in a dye bath, the removal of the excess disperse dyestuffs dyeing the polyester and/or split microfiber spunbond nonwovens being carried out simultaneously with the vatting, using reduction media such as sodium dithionite, glucose or sodium sulfide. Dyeing in only one dyeing bath improves dyeing economy, since fewer chemicals, less water and only one installation are required.
Nonwoven fabrics are preferably used as the textile materials in the method. These pricewise very reasonable materials can be improved in this manner by dyeing technology.
Advantageously, split microstaple fiber or spunbonded nonwoven fabrics are used as the textile materials. Surprisingly, the known difficulties in dyeing these microfiber nonwoven fabrics were able to be overcome.
Microfilament nonwoven fabrics made of spun-dyed polyester and/or polyamides are particularly preferred. In the case of these microfilament nonwoven fabrics, both lightfastness and wetfastness are further increased.
In the following, the present invention is explained in greater detail as given in five exemplary dyeing methods. As a comparison, dyeing using disperse dyestuff and subsequent dyeing using an acid dyestuff is carried out in the same manner with three color shades. The results of the evaluation of colorfastness are assembled in Table 2.